Patent GB-762468-A (GB)
Title: Improvements in processes for the catalytic oxidation of acetone
Inventor: BATION EDMUND
IPC: G01N31/22
Filed: 1953-05-08
Abstract: Acetone is oxidized in the liquid phase at elevated temperature and at normal or elevated pressure by passing therethrough a stream of oxygen or an oxygen-containing gas in the presence of an oxidation catalyst, the reaction being carried out at between 65 DEG  C. and the boiling-point of acetic acid under the pressure conditions obtaining, and withdrawing continuously as they are formed acetic acid, formic acid and formaldehyde in gaseous form entrained in the said gas stream.  The escape of the volatilized reaction products from the reaction zone is assisted by passing the gas upwardly through the reaction mixture.  The gas may consist of relatively pure oxygen or oxygen diluted with one or more inert gases, e.g. in the form of air or air supplemented by an additional quantity of nitrogen.  In a preferred form of the invention molecular oxygen and acetone are introduced into a heated liquid medium consisting wholly or partly of acetic acid and containing the catalyst which is preferably a manganese salt, the reaction being effected in a column equipped with controllable heating means and connected to a separate (non-reflux) condenser in which the condensate is collected.  The molecular oxygen is introduced at the base of the column and the acetone is continuously introduced into the liquid contained in the column.  The oxidation products and unchanged acetone are condensed in the condenser and fractionated in the usual manner. At the commencement of the operation the column may be charged with acetone or with a "foot" originating from a previous operation of the process instead of with acetic acid.  When operating near the upper end of the specified temperature range it is preferred to introduce acetic acid simultaneously with acetone into the column in order to maintain a constant level in the column.  The process may be carried out above the normal boiling-point of acetic acid by working under pressure. When using air instead of molecular oxygen for the oxidation it is preferable to operate the process under pressure.  In examples: (1) a column provided with a jacket for circulation of water or steam is provided in its lower part with a plate of fritted glass and is surmounted by two pouring funnels which discharge into a tube inside the column.  The column is connected to a non-reflux condenser and is charged with the "foot" from a previous operation of the process and consisting of acetic acid mixed with formic acid and acetone and a small amount of formaldehyde. Manganese nitrate is added as catalyst and oxygen is introduced at the bottom of the column.  The temperature is raised to and maintained at 90 DEG  C. and as the distillation commences acetone and acetic acid are poured in via the two funnels while maintaining the level in the column constant.  The oxygen introduced entrains the products (acetic acid, formic acid, formaldehyde and unchanged acetone) in a gaseous state and these are then condensed in the condenser; (2) as in (1) except that the oxidation is carried out at 110 DEG  C.; (3) the reaction is carried out in a stainless steel tube surrounded by a double envelope to allow heating and cooling and provided in the lower half with an air entry which comprises a valve through which acetone mixed with acetic acid is introduced with the aid of a regulating pump.  The reactor leads to two condensers which can function under pressure, one being cooled by water and the other by brine.  The reaction is carried out at 89 DEG  C., air or a mixture of air and nitrogen being introduced under pressure whilst acetone and acetic acid are introduced into the reactor charged with acetic acid, acetone and manganese nitrate. Acetic acid, formic acid, and formaldehyde are recovered from the volatile products entrained in the gas mixture.  A comparative example is also given in which the process is carried out in a vessel as in (1) but surmounted by a condenser working at total reflux, the products being withdrawn in liquid form through the base of the column.  The column is charged with acetic acid, acetone, and manganese nitrate.  Oxygen is introduced and the column maintained at 90 DEG  C. whilst acetone is continuously poured into the top of the column and an equivalent quantity of liquid is drawn off at the bottom.  The amount of the various oxidation products obtained show that the total yield of formic acid and formaldehyde and the yield of formaldehyde alone are lower than those obtained by the process of the invention.